SINTERING OF PARTIALLY-STABILIZED ZIRCONIA AND PARTIALLY-STABILIZED ZIRCONIA-HYDROXYAPATITE COMPOSITES BY HOT ISOSTATIC PRESSING AND PRESSURELESS SINTERING

In this study two sintering techniques, pressureless sintering (PS) an d hot isostatic pressing (HIP), were used for comparing the sinterabil ity of two yttria-partially-stabilized zirconia/hydroxyapatite (PSZ/HA ) composites. Virtually dense ceramics were obtained using HIP at a ma ximum pressure of 160 MPa for 1 h at 1225 degrees C for both PSZ powde rs and their HA composites. The ceramic bodies, produced using PS at t he same temperature as in the HIP process and higher, had densities fr om 80% to 97% of theoretical density, depending on the properties of t he PSZ powders. FTIR spectra of composites sintered by HIP and PS at 1 225 degrees C were compared, indicating a degradation of HA by PS but no degradation by HIP. The bending strength of HIPed ceramics was meas ured and found to be high. It is concluded that it is possible to prod uce dense PSZ/HA composites by the HIP or PS processes. For the PS, th e reactivity of powders is the key factor during the densification. Th e HIP technique is the preferable technique for producing stable and d ense HA-containing composites. (C) 1996 Elsevier Science Limited.